AJP - Gastrointestinal and Liver Physiology, Vol 265, Issue 1 149-G155, Copyright © 1993 by American Physiological Society
Cholecystokinin receptors and PANC-1 human pancreatic cancer cells
J. P. Smith, C. A. Rickabaugh, P. J. McLaughlin and I. S. Zagon
Department of Medicine, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey 17033.
The gastrointestinal peptide cholecystokinin (CCK) has been shown to
stimulate growth of human pancreatic adenocarcinoma in vitro and in vivo,
although CCK receptors have not been identified in pancreatic cancer cells.
The purpose of this study was to characterize the CCK receptors in
pancreatic cancer cells and to correlate the receptor binding studies with
the trophic action of CCK agonists and antagonists. With the use of
homogenates of PANC-1 human pancreatic cancer cell line grown in culture,
the binding of 125I-labeled CCK octapeptide (125I-CCK-8) was examined under
various conditions to characterize the CCK receptor. Specific and saturable
binding of 125I-CCK-8 was detected in PANC-1 cells; data were consistent
with a single binding site. Scatchard analysis yielded a binding affinity
[dissociation constant (Kd)] of 2.8 nM and a binding capacity of 26 fmol/mg
protein. Binding was dependent on protein concentration, time, temperature,
the presence of protease inhibitors, and pH and was sensitive to Na+, K+,
Mg2+, and ethylene glycolbis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic
acid. Competition experiments indicated that L-365,260, a selective CCK-B
(gastrin) receptor antagonist, was the most potent displacer of 125I-CCK-8,
and no significant displacement of binding was found with the selective
CCK-A receptor antagonist. Growth of PANC-1 cells in culture was stimulated
by CCK at a concentration consistent with the Kd, and CCK-stimulated growth
was inhibited by the CCK-B receptor antagonist (L-365,260) not the CCK-A
receptor antagonist (L-364,718).(ABSTRACT TRUNCATED AT 250 WORDS)
